A samurai army marches through the hills of the Iga province of Japan. The landscape is covered
in dense trees and sheer rock faces, making it a perfect spot for an ambush by stealth ninjas.
From the trees, the Iga warriors watch as the invading force approaches the kill zone. They
are camouflaged to blend in with the forest. The invading samurai led by Nobukatsu of the Oda clan
march towards their demise. There is movement in the trees and rocks surrounding the valley.
Then without warning, ninja warriors seem to appear out of thin air. They use guerilla hit and
run tactics, slashing the invading samurai with their swords as they glide across the forest path,
only to disappear back into the trees. The invading Oda samurai
are forced to retreat to the safety of their home province to regroup.
The Tenshō Iga War is the name given to two invasions on the province of Iga in 1579
and 1581 by the Oda clan. At the time, Japan was divided into many different territories
controlled by Shogun. The Shogun used their militaries to keep command of their land
and invade other territories to gain power and resources. Japan as a whole had an emperor who
all Shogun were supposed to report to, but really the emperor had very little
power. He was just a figurehead, the Shogun were really the ones in charge.
During this time we can think of the ruling elites of Japan, or Shogunate,
as similar to the kings of Medieval Europe. In fact, the enetire Shogunate system was akin to
the feudal system of Europe. The Shogun were like kings, their samurai were knights, and the
peasants were still peasants. Shogun expanded or gained new territory using their samurai armies.
For a long period of time the Oda clan had their sights set on invading Iga province.
Unfortunately for Oda Nobunaga, the ruler of the Oda clan, Iga was a natural fortress.
The province was surrounded by mountains on all sides and could only be entered through
narrow valleys. These valleys were prime spots for ambushes by the Iga samurai and ninjas.
Oda Nobunaga had secured almost all land surrounding Iga province. But the land was still
too protected by its natural topography and highly trained warriors for Nobunaga to conquer. So, Oda
Nobunaga set his sights on a different province. In 1567 he began his invasion of Ise province
just to the east of Iga province. The Oda clan was victorious, and as part of the peace agreement
the leader of the Kitabatake clan of Ise adopted Nobunaga's son Nobukatsu as his heir. This meant
that although the Oda clan did not officially rule Ise, they were in control of the territory.
To make the authority of the Oda clan in the region even more prominent,
they began to assassinate the remaining members of the Kitabatake clan.
With each death the Oda clan became more powerful in the region. The assassinations
continued until the Oda clan controlled the entire Ise region, even though the
peace agreement had said the Kitabatake clan could remain in power. Now the Oda clan had
the samurai numbers and resources to finally take Iga province, but it would not be easy.
The young Nobukatsu, son to the Oda clan leader Oda Nobunaga, was ambitious and wanted to prove
to his father he would be a great Shogun. He decided to expand the domain of Ise by
invading Iga province. In 1578 Nobukatsu started preparations for his invasion.
He sent samurai and builders into the outskirts of the Iga province. There he
had secretly planned to construct a castle that would serve as a staging ground for his campaign.
Unfortunately for the men that Nobukatsu sent into Iga province, the leaders were alerted
by Iga ninjas of the castle being built. Their response, unrelenting ninja warfare.
The samurai and ninjas of Iga decided to attack the castle before it could be constructed. On
November 24, 1578 they attacked in broad daylight. The Iga warriors used stealth tactics to surround
the workers. They caught the builders and Oda samurai off guard. From out of the forest ran
hundreds of Iga warriors. Their swords tore through the meager defenses of the secret castle.
The Oda clan and builders had to go into a full retreat, or be slaughtered by the Iga attackers.
They left everything behind and made their way back to Ise province as fast as possible.
After the Iga forces had dealt with the Oda builders and samurai they brought torches
to the half built castle. To make sure the structure couldn’t be completed they burned
it to the ground, sending a clear message that the Oda clan would have to do much
better if they ever stood a chance of taking over the Iga province.
Nobukatsu was surprised and embarrassed to hear of the total loss of his castle
and insolence of the Iga warriors. He sent samurai back into Iga province to make them pay.
But the Iga warriors met them in one of the valleys of the region. Using the landscape
to their advantage they quickly defeated the Oda clan for the second time. This only
infuriated Nobukatsu even more. He tried to amass a larger army to march into Iga for a third time,
but his advisors persuaded him to wait. Unable to quench his thirst for revenge Nobukatsu
devised a three-pronged invasion to defeat the Iga warriors and claim their territory.
The attack began on October 6, 1579. It would not end well for Nobukatsu and the Oda clan.
The Iga leaders, through their network of spies, found out about Nobukatsu’s
plan to invade and made preparations. The Iga warriors set up ambushes along the paths that
the Oda forces would have to take to enter Iga province. They knew just where to lie in wait.
8,000 of Nobukatsu’s men entered Iga province through Nagano Pass.
The Iga warriors used guerilla tactics to throw the invading army off guard. They confused the
Oda samurai by attacking from different areas at different times. It was impossible for the
invading force to know where the next attack would come from. The Oda samurai began to take heavy
losses. Nobukatsu was forced to retreat, leaving countless soldiers behind to their slaughter.
The two other forces that Nobukatsu dispatched at the same time were much smaller, only consisting
of around 1,500 men each. They met a similar fate to the main army. The Iga warriors used
surprise attacks to sow chaos within their ranks. Then they slowly picked apart the
confused and separated sections of the army. One of Nobukatsu’s head generals lost his life trying
to escape the warriors of Iga province. Thousands of Oda samurai were lost in only a few days.
These massive defeats marked the end of Nobukatsu’s campaign into Iga province.
But that wasn’t the worst news for Nobukatsu. He had carried out this campaign without
consulting with his father Nobunaga, who was still head Shogun of the Oda clan.
Nobunaga was furious. Nobukatsu had wanted to prove to his father he could be a strong leader,
but failed in that mission and brought shame upon himself. Nobunaga threatened to disavow his son,
but ended up forgiving him. Although, he did take away much of his son’s power.
Nobunaga could not let Iga province grow any stronger.
He had to show that the Oda clan was the mightiest force in the region. Nobunaga
met with advisors and war generals. He worked through the difficulties of taking Iga province
and what was needed to do it successfully. Two years after his son’s failed invasion,
Nobunaga would launch his own. It would become known as the Second Tenshō Iga War.
On September 30, 1581 the invasion began. It was on a much larger scale than the previous
attempts by his son. In fact, it made the earlier invasions look like child’s play.
At this point in time Oda Nobunaga was one of the most powerful Shoguns in all of Japan. He
controlled most of the central area of the country. The most frustrating thing about
Iga province to Nobunaga was that it was right in the middle of his territory. He controlled
the land surrounding Iga province, but had not yet been able to conquer Iga province itself.
He needed to control this land in order to unify the entire region under his control.
Oda Nobunaga assembled a huge army to defeat Iga province. An army so large that they would be able
to force their way past any ambushes or traps the Iga warriors might lay for them. He decided
to attack Iga province from all directions, causing the Iga army to split their troops,
thus minimizing the effectiveness of their military. Oda Nobunaga sent 12,000 samurai
in from the northeast, 10,000 samurai in from the southeast, 7,000 samurai from the north,
another 7,000 from the southwest with a second force of 3,700 samurai entering right behind them,
and 2,300 samurai from the northwest. The total force of Nobunaga’s massive
army was around 42,000 men. The Iga province army totalled around 10,000
and was spread throughout the region. They didn’t stand a chance.
But the Iga province warriors fought bravely. They continued to employ guerilla and stealth tactics.
They made small dents in the invading forces, but there were just too many Oda clan samurai. The
Iga province warriors were forced to retreat to Hijiyama Castle in the north and Kashiwara Castle
in the south, where they were besieged by the Oda forces. Nobunaga sent wave after wave of samurai
to attack the castles. He kept any supplies from getting to the Iga warriors, eventually
causing them to surrender. The final forces at Kashiwara Castle surrendered on October 8,
1581, thus ending any further resistance to Oda Nobunaga and his clan. Iga province had fallen.
In November, Nobunaga surveyed all of the land of Iga province. Satisfied by the gains he and
his army had made, he withdrew his troops and put his son Nobukatsu in control of the area.
Even though his son had disgraced him, he forgave Nobukatsu and allowed him to rule the
new Oda province that had once given the clan so much trouble. But how were the warriors of
Iga province able to fight off so many invading samurai? How did they defeat much larger forces
in the first Tenshō Iga War? Part of it had to do with their knowledge of
the land, but there was something else at play. Something that is pretty shocking.
It is believed by many scholars that the ninja order started in Iga province.
These elite fighters trained in espionage and guerilla tactics would have made the
warriors of Iga province especially deadly. This may have been why they
were able to fight off the Oda clan for so long. After the war came to the end,
Iga warriors were hired as auxiliary troops for other military forces. Their skills and
abilities to infiltrate and secure secrets from enemies were legendary across Japan.
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